The present invention relates to a device and method for inspecting the outer appearance of card-like articles made of a single material such as plastic, paper, metal, wood or the like or of a composite material thereof.
So far cards have been widely used in various fields such as banks, railways, etc., but the outer appearances of such cards have been visually inspected by inspectors. That is, the inspectors turn up cards one by one to inspect them. The operation for manually turning up cards one by one so as to expose the whole surface of each card is tedious and only an experienced and skilled inspector can handle a large number of cards. Thus it is extremely difficult to increase the speed of card inspection.
If the speed of card inspection is increased, it becomes impossible for an inspector to visually check the whole surface of each card. Furthermore, if the visual card inspection is continued for a long time, the inspector is fatigued thereby decreasing the card inspection speed and resulting in many erratic inspections. As a result, the cards must be inspected twice or thrice.
Various inspection devices have been proposed and demonstrated in order to inspect the cards while they are being produced, but erratic inspections tend to occur very frequently due to the erratic displacement of the position of an image. Furthermore, the inspection speed is not so fast. Moreover, there has not been proposed a practical inspection device in which the transfer of articles to be inspected is taken into consideration.